1. Field of the Invention
The present invention relates to an air-conditioning system having at least two evaporators.
2. Description of the Related Art
In the past, as a vehicular air-conditioning system, there has been one provided with a compressor compressing a refrigerant, a condenser cooling a refrigerant discharged from the compressor, a front seat expansion valve reducing the pressure of the refrigerant discharged from this condenser, a front seat evaporator evaporating a refrigerant from this front seat expansion valve to cool the air, a rear seat expansion valve arranged in parallel with a front seat expansion valve in the flow of refrigerant from the compressor, and a rear seat evaporator evaporating refrigerant from the rear seat expansion valve to cool the air (for example, see Japanese Patent Publication (A) No. 5-296586).
This system is provided with a temperature sensor for detecting the temperature of the vented air from the front seat evaporator and an electronic control system for controlling the compressor based on a detection value of this temperature sensor so as to make the temperature of the vented air of the front seat evaporator close to a target temperature TEO.
In the above vehicular air-conditioning system, when setting the target temperature TEO of the vented air temperature of the front seat evaporator at an extremely low temperature, the vented air temperature of the temperature sensor is made to approach the target temperature TEO by increasing the discharge capacity of the refrigerant of the compressor. For this reason, the flow rates of the refrigerant flowing into the front seat evaporator and rear seat evaporator are also increased. At this time, if the blowing rate of the rear seat blower is small, the amount of heat absorbed by the refrigerant at the rear seat evaporator becomes smaller, so the surface of the rear seat evaporator is frosting up and the vented air temperature of the rear seat evaporator can no longer be adjusted.